The NAT Port Mapping Protocol (NAT-PMP) is the direct concurrent to the
UPnP IGD specification: it provides a way to do NAT traversal and it's
part of the Bonjour protocol specifications.
libnatpmp is an attempt to make a portable and fully compliant
implementation of this protocol for the client side. It is based on
non-blocking sockets and all calls of the API are asynchronous.
